Ernst II Ludwig of Saxe-Gotha-Altenburg
Son of Frederick III and Luise Dorothea of Saxe-Gotha-Altenburg. Married (1769) Princess Charlotte of Saxe-Meiningen, a younger cousin of his mother, with whom he had four sons: Ernst (1770-1779), Emil Leopold August (1772-1822), Frederick (1774-1825) and Ludwig (1777-1777).
He succeeded to the duchy of Saxe-Gotha-Altenburg on the death of his father in 1772 and became known as a liberal and enlightened ruler. In 1787 he began planning, with astronomer Frans Xaver von Zach, the establishment of an astronomical observatory (the Gotha Observatory, or Sternwarte Gotha), which would secure Gotha's place as an international center of astronomy in the 19th century. The observatory closed in 1934.
In 1774 he became a freemason and in 1783 a member of the Illuminati.
During his visit to the court of Saxe-Gotha-Altenburg on October 17, 1764, Boswell described Ernst Ludwig, then hereditary prince of the duchy, as "mild & quiet".